Standardized uptake values of (68)Ga-DOTANOC PET: a promising prognostic tool in neuroendocrine tumors

Despite the fact that several studies have been published regarding the prognostic factors of neuroendocrine tumors (NETs), there are some cases in which available data are not sufficient to predict disease progression and to define a correct therapeutic approach. To our knowledge, the role of maximum standardized uptake value (SUVmax) as a prognostic factor has never been studied in NET patients. Therefore, we prospectively investigated whether (68)Ga-[1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-NaI3-octreotide ((68)Ga-DOTANOC) PET SUVmax could be used as an accurate noninvasive marker for disease prognosis.

Forty-seven patients with NETs were studied with (68)Ga-DOTANOC PET. All patients underwent a baseline visit and laboratory and radiologic examinations. Follow-up was performed in all cases.

SUVmax was significantly higher in patients with pancreatic NET and in those with well-differentiated NETs. Moreover, SUVmax was significantly higher in patients with an elevated expression of 2A-somatostatin receptor. During the follow-up, the disease was stable or presented a partial response in 25 patients, and in 19 cases the disease progressed. The patients with stable disease or a partial response had an SUVmax significantly higher than did those in the progressive disease group, with the best cutoff ranging from 17.9 to 19.3. At univariate and multivariate analysis, the significant positive prognostic factors were well-differentiated NET, an SUVmax of 19.3 or more, and a combined treatment with long-acting somatostatin analogs and radiolabeled somatostatin analogs.

We demonstrated, for the first time to our knowledge, that (68)Ga-DOTANOC PET SUVmax correlates with the clinical and pathologic features of NETs and is also an accurate prognostic index.